Against the Christians (Greek: Κατὰ Χριστιανῶν; Adversus Christianos) is a late-3rd century book written by Roman-Phoenician Neoplatonic philosopher Porphyry of Tyre, criticizing the writings of Christian philosophers and theologists. Due to widespread censorship by Christian imperial authorities, no known copies of this book exist. Only through references to it in Christian writings attacking it can its contents be reconstructed.